Sheet materials, in particular, sheet vinyl flooring products, made with chips or other particulate material, are commonly referred to as inlaids. Inlaid floorcoverings are normally characterized as those which maintain their decorative appearance as the surface is worn or abraded away. This characteristic makes such products particularly suitable for use in commercial areas where significant wear is encountered. These products and processes for their manufacture are well known in the floorcovering business and originate back to the early linoleum times where through-patterned floorcoverings, based on linseed oil, cork dust and resins were developed by the industry. The process was later modified for vinyl.
Vinyl inlaid floorcovering consists of coarse, colored particles, such as chips or dry blends, which are "laid on" a substarate and then sintered by heat, or "laid in" a transparent or transluscent liquid or solid matrix and fused by heat and/or pressure. The chips are produced from pre-gelled or fused, spread, calendered or extruded compounds cut into geometrically regular profiles or ground into randomly shaped particles.
The dry blends are made by mixing fine PVC powder with pasticizer, filler and color pigments and heating above the PVC compound's softening temperature. The small original particles "grow" and form a loose, porous, coarse, fluffy mass.
Currently, to produce registered inlaid patterns for sheet vinyl, conventional manufacturing procedures distribute the coarse particles on the substrate in diffrent steps with the help of area-complementary stencils, followed by topcoating with a clear wearlayer. This method is complicated and can only be used to produce large geometric patterns.
Modern inlaids generally fall into two classifications: resilients and non-resilients. Resilients include a substantially continuous layer of foam and are usually made by incorporating solid particulate material into a plastisol coating, followed by gelling and fusing. Non-resilients do not contain a foam layer and usually are made by sintering and/or calendering, or otherwise compacting, particulate material.
The non-resilient products commercially offered are those containing large (about 1/8 inch) square chips in a clear matrix and those containing small (about 0.004 inch) dry blend resin particles made by sintering and/or compacting normal dry blend resins.
While construction of inlaid products by compaction from discreet chips or particles (normally of different colors) offers distinct styling opportunities, a significant premium is paid in terms of expensive, cumbersome equipment. Furthermore, the nature of the process restricts the range of designs available. For example, in order to effect specific registered pattern definition, it is necessary to deposit chips of different colors in preselected areas on the sheet. This is difficult mechanically, and results in a slow cumbersome process which does not produce finely defined designs.
Some of the inherent difficulties in current production techniques for non-resilient inlaids have been minimized by use of increasingly sophisticated materials and design techniques, such as using fine particle size, dry blend resins, printing over the surface of the resulting inlaid product and, optionally, embossing, with and without application of a wearlayer. Unfortunately, whereas the use of the finer particle size preserves the specific characteristic of an inlaid product, i.e. the pattern does not change as the product wears through, overprinting the product, whether or not a wear layer is applied, essentially negates this charecteristic because wearing through the print layer essentially destroys the pattern. This eliminates the product from commercial, high-use environments and limits its utility principally to styling effects in residential and related applications.
Resilient inlaids are usually made by embedding ground plastic particulate material in a plastisol coating. U.S. Pat. No. 4,212,691 exemplifies such products and methods for their manufacture. One of the limitations of such technology, as taught, for example, in U.S. Pat. No. 4,126,727, is the substantially uniform appearance of relatively small decorative particles, chips or flakes produced by simply dispersing them uniformly in the wear layer.
It is, therefore, a principal purpose and object of this invention to provide real through-patterned inlaids and, in particular, inlaids with registered patterns, having heretofore unobtainable decorative effects. It is also an important purpose and object of this invention to provide a novel process for producing such inlaids which is believed to be simpler than current inlaid production technology. Other purposes and objects of the invention will be apparent from the following discussion.